Described below is an elevator system with a shaft door device and a cab door device.
Elevator systems must, particularly if they are intended to carry passengers, possess various safety mechanisms in order to comply with safety requirements. For example, it must be ensured that an opened shaft door of a shaft door device is automatically closed in the non-coupled state, so that a person cannot fall into the elevator shaft. The elevator shaft is the shaft in which the elevator cab can travel upwards and downwards. A non-coupled state exists when the cab door device, which is a part of the elevator cab, is not in the same position (stopping point in the shaft) as the shaft door device in the corresponding shaft. In particular, in the non-coupled state there is no operative mechanical connection between the shaft door device and the cab door device, i.e. they are not coupled to one another. Automatic closing of the shaft door must also be assured, in particular when the shaft door device is in a currentless state. For this purpose the shaft door device of the elevator system usually has a shaft door closer that ensures that the shaft door of the shaft door device automatically assumes the closed position in the opened non-coupled state. As it is also necessary for this mechanism to be assured in the currentless state it is not possible to use an electric motor as a shaft door closer. In most cases therefore the shaft door closer is embodied by a weight that is operatively connected to the shaft door by a wire rope pulley fed over a guide roller such that a closing force F2 is exerted onto the shaft door, particularly in the opened state, so that the shaft door is moved in the direction of the closed position. In most cases, the closing force F2 caused by the shaft door closer acts on the shaft door without interruption, so that the closing force F2 acting counter to the opening direction must also be brought to bear in order for the shaft door to be opened.
An elevator system stops at multiple floors, and it can be the case that the shaft doors on the individual floors are embodied differently. Consequently, it can also be the case that the shaft door closer in particular and, as a result, the closing force F2 acting on the shaft door, vary. It is thus possible, depending on the floor, for differing closing forces F2 to be exerted onto individual shaft doors by the shaft door closer, the forces having to be overcome in order for the door to open each time the cab door device comes to a stop with the cab. If the shaft door closer is, for example, embodied as a weight, the weight usually has a mass of approx. 3 to 10 kg, depending on the particular shaft door.
Usually, for the purpose of opening a shaft door, the cab door device is coupled to the shaft door device in order to establish an operative mechanical connection between the cab door device and the shaft door device. The coupling can, for example, be achieved by a bar that is located on the cab door device and, when the cab door device stops at the corresponding position in the shaft (stopping point in the shaft), establishes an operative mechanical connection to the shaft door device, so that forces can be transferred by the cab door device to the shaft door device, and in particular to its shaft door, or vice versa. The opening of one of these doors is usually directly driven by an electric motor. As the two doors are connected to one another in the coupled state, for example by the bar, the forces of the electric motor are also transferred to the coupled door, so that in addition to the door directly driven by the electric motor, the door coupled to the directly driven door is also opened. If, for example, the cab door is opened directly by the electric motor, the shaft door is also opened, as a result of the operative mechanical connection between the cab door and the shaft door. As soon as the two doors (cab door and shaft door) are coupled to one another both doors can be opened by the electric motor. As the electric motor is in most cases housed in the cab door device and directly drives the cab door, the shaft door is in most cases opened as a result of the operative mechanical connection between the shaft door and the cab door. The shaft door is thus indirectly opened via the electric motor.